Manufacture of paper-pulp.



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SIDNEY D. WELLS, MADISON, WISCONSIN; DEDICATED, BY MESNE ASSIGNMENTS, TO THE GOVERNMENT OF THE UNITED STATES AND TO THE PEOPLE OF THE UNITED STATES.

MANUFACTURE OF PAPER-PULP.

No Drawing.

Specification of Letters Patent.

Patented June 4i, T9118.

(DEDICATED T0 THE PUBLIC.)

To all whom it may concern:

Be it known that I, SIDNEY D. WELLS, a citizen of the United States, residing at Madison, in the county of Dane and the State of Wisconsin, (whose post-office address is R. F. D. #4, Madison, Wis.,) have invented a new and useful Improvement in the Manufacture of Paper-Pulp.

This application is made under the act of March 3, 1883, chapter 143 (22 Stat. 625), and the invention herein described and claimed may be used by the Government of the United States, or any of its oficers or employees, in the prosecution of work for the Government, or any person in the United States, without payment to me of any royalty thereon,

My invention relates to .the manufacture of paper pulp by alkaline processes from wood or other materials of a fibrous nature whereby the yield and quality of pulp obtained is increased while the consumption of chemical and duration of cooking is decreased.

The object of 'the invention is to add spent cooking liquor, usually known in the art as black liquor, to the charge during the cookin operation whereby the concentration 0 the active chemicals are reduced, and their action on the cellulose is diminished while their action on the incrusting material remains the same.

In the practice of the invention, the process is carried out in the following manner: The material of a fibrous nature is prepared by any of the means now practised in the art and charged into the-digester as in common practice. The cooking liquor is also added and any preliminary operations, such as steaming, distillation of volatile oils, preliminary penetration, and the like, may be followed as desired. Steam is then admitted to the digestcr and the contents are brought up to the desired cooking presure. When the temperature in the digester is sufficient to cause the cooking liquor actively to attack the incrusting material, spent lyes are admitted in the digester, in addition to the moisture carried in by the steam, in sufficient quantity for effecting the reduction of the concentration of the active chemicals employed in the cooking while the action of the active chemicals on the cellulose is diminished and their action on the incrusting material remains the same. The use of the spent lyes in this manner operates to increase not only the yield but also the quality of the pulp produced. The cook is carried out by any of the means commonly practised in the art.

In patent application recently filed by applicant concerning a new process for making soda pulp, the benefits of the addition of moisture during the cook are described. This practice had the disadvantage that the spent cooking liquor was being diluted, which entailed the added expense of evaporation of additional water in the recovery of the soda. In the process described herein, this disadvantage is avoided by using spent cooking liquors from earlier cooks. The concentration of the active chemicals are thereby reduced during thecook without diluting the black liquor that will be secured in the subsequent washing of the same.

Having thus described my invention, I claim:

A process of cooking wood or other fibrous material for the production of paper pulp in which the concentration of active chemlcals during the cook is reduced ,to the desired degree by the introduction of spent lyes while the cock is proceeding whereby the cellulose is protected to a marked degree from the action of the cooking liquors while their action on the incrusting matter is in no way. diminished.

In testimony, I afiix my signature in the presence of two subscribing witnesses.

SIDNEY D. WELLS.

Witnesses:

O'rro HEERR, Gr. C. MoNAUcH'roN. 

